dt-bindings: pinctrl: sunxi: Fix reference to driver

dt-bindings: pinctrl: sunxi: Fix reference to driver

BugLink: http://bugs.launchpad.net/bugs/1794889
[ Upstream commit b614e905a0bc8fc5d4fa72665ac26ae00c874a4e ]

Bindings describe hardware, not drivers.
Use reference to hardware Allwinner A1X Pin Controller instead driver.

Signed-off-by: Matheus Castello <matheus@castello.eng.br>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>